Curable compositions and rapid prototyping process using the same

ABSTRACT

The present invention provides curable compositions and rapid prototyping processes using the same. In one embodiment, the present compositions include one or more aromatic epoxies and one or more aliphatic epoxies, and, after full cure, exhibit a heat deflection temperature of at least 105° C. and an elongation at break of at least 1.5%.

FIELD OF THE INVENTION

The present invention relates to curable compositions capable ofproviding articles having the combination of a good elongation at breakand good high temperature resistance. In addition, the present inventionrelates to applications for such compositions, such as their use inrapid prototyping processes.

BACKGROUND

In the field of curable compositions, for instance in the field of rapidprototyping compositions, high temperature resistance, elongation tobreak, and cure speed are relevant parameters. Unfortunately, acomposition providing good high temperature resistance often exhibits apoor elongation to break. One of the objectives of the present inventionis to provide compositions yielding both a good high temperatureresistance and a good elongation to break. Another objective is toprovide compositions that furthermore have a good cure speed.

Examples of prior curable compositions are set forth in, for instance,U.S. Pat. No. 5,476,748; U.S. Pat. No. 5,707,780; U.S. Pat. No.5,972,563; U.S. Pat. No. 5,981,616; U.S. Pat. No. 6,313,188; U.S. Pat.No. 6,368,769; European Patent Application 0360869; and Japanese PatentApplication 11199647.

SUMMARY

The present invention provides compositions having both a good hightemperature resistance and a good elongation to break. Furthermore, thepresent invention provides compositions that additionally have a goodcure speed. Also, the present invention provides applications for thecompositions, such as their use in a rapid prototyping process.

In one embodiment, the present invention provides a curable compositioncomprising:

(i) one or more aromatic epoxies; and

(ii) one or more aliphatic epoxies;

wherein said composition, after full cure, has a heat deflectiontemperature under a pressure of 1.82 MPa of at least 105° C. and anelongation at break of at least 1.5%.

In another embodiment, the present invention provides a curablecomposition having an E10 cure speed of less than 80 mJ/cm² and, afterfull cure, a heat deflection temperature under a pressure of 1.82 MPa ofat least 1 25° C. and an elongation at break of at least 2.5%.

Additional objects, advantages and features of the present invention areset forth in this specification, and in part will become apparent tothose skilled in the art on examination of the following, or may belearned by practice of the invention. The inventions disclosed in thisapplication are not limited to any particular set of or combination ofobjects, advantages and features. It is contemplated that variouscombinations of the stated objects, advantages and features make up theinventions disclosed in this application.

DETAILED DESCRIPTION

(A) Cationically Curable Component

The present compositions comprise at least one cationically curablecomponent, e.g. at least one cyclic ether component, cyclic lactonecomponent, cyclic acetal component, cyclic thioether component, spiroorthoester component, epoxy-functional component, and/oroxetane-functional component. Preferably, the present compositionscomprise at least one component selected from the group consisting ofepoxy-functional components and oxetane-functional components.Preferably, the compositions comprise, relative to the total weight ofthe composition, at least 20 wt % of cationically curable components,for instance at least 40 wt %, at least 60 wt %, at least 70 wt%, or atleast 80 wt %. Generally, the compositions comprise, relative to thetotal weight of the composition, less than 99 wt % of cationicallycurable components, for instance less than 95 wt %, less than 90 wt %,or less than 85 wt %.

(A1) Epoxy-Functional Components

The present compositions preferably comprise at least oneepoxy-functional component, e.g. an aromatic epoxy-functional component(“aromatic epoxy”) and/or an aliphatic epoxy-functional component(“aliphatic epoxy”). Epoxy-functional components are componentscomprising one or more epoxy groups, i.e. one or more three-member ringstructures (oxiranes) according to formula (1):

(A1-i) Aromatic Epoxies

Aromatic epoxies are components that comprise one or more epoxy groupsand one or more aromatic rings. The compositions may comprise one ormore aromatic epoxies, e.g. two or more aromatic epoxies or three ormore aromatic epoxies.

Examples of aromatic epoxies include aromatic epoxies derived from apolyphenol, e.g. from bisphenols such as bisphenol A(4,4′-isopropylidenediphenol), bisphenol F(bis[4-hydroxyphenyl]methane), bisphenol S (4,4′-sulfonyldiphenol),4,4′-cyclohexylidenebisphenol, 4,4′-biphenol, or4,4′-(9-fluorenylidene)diphenol. The bisphenols may be alkoxylated (e.g.ethoxylated and/or propoxylated) and/or halogenated (e.g. brominated).Examples of bisphenol epoxies include bisphenol diglycidyl ethers.

Further examples of aromatic epoxies include triphenylolmethanetriglycidyl ether, 1,1,1-tris(p-hydroxyphenyl)ethane triglycidyl ether,and aromatic epoxies derived from a monophenol, e.g. from resorcinol(for instance resorcin diglycidyl ether) or hydroquinone (for instancehydroquinone diglycidyl ether). Another example is nonylphenyl glycidylether.

In addition, examples of aromatic epoxies include epoxy novolacs, forinstance phenol epoxy novolacs and cresol epoxy novolacs. Commercialexamples of cresol epoxy novolacs include, e.g., EPICLON N-660, N-665,N-667, N-670, N-673, N-680, N-690, and N-695, manufactured by DainipponInk and Chemicals, Inc. Examples of phenol epoxy novolacs include, e.g.,EPICLON N-740, N-770, N-775, and N-865, manufactured by Dainippon Inkand Chemicals Inc. Examples of epoxy novolacs also include thosecomponents represented by the following formulae (2), (3), or (4):

wherein

-   -   R₁ represents a hydrogen atom or a methyl group;    -   R₂ represents a hydrogen atom, an alkyl group having 1-4 carbon        atoms (e.g. a methyl-ethyl-, isopropyl-, or t-butyl group), a        phenyl group, or an aralkyl group having 7-10 carbon atoms;    -   n represents an integer of 1-12 (e.g. 2-12 or 1-5);    -   R₃ represents a hydrogen atom or an alkyl group having 1-3 atoms        (e.g. a methyl-, ethyl-, or n-propyl group); and    -   R₄ represents a hydrogen atom or an alkyl group having 1-3 atoms        (e.g. a methyl-, ethyl-, or n-propyl group).

Examples of aromatic epoxies are also listed in U.S. Pat. No. 6,410,127,which is hereby incorporated in its entirety by reference.

Preferably, the present compositions comprise, relative to the totalweight of the composition, at least 10 wt % of one or more aromaticepoxies, e.g. at least 25 wt %, at least 40 wt %, at least 45 wt %, atleast 50 wt %, or at least 55 wt %. Generally, the present compositionswill comprise, relative to the weight of the composition less than 90 wt% of one or more aromatic epoxies, for instance less than 80 wt %.

(A1-ii) Aliphatic Epoxies

Aliphatic epoxies are components that comprise one or more epoxy groupsand are absent an aromatic ring. The compositions may comprise one ormore aliphatic epoxies.

Examples of aliphatic epoxies include glycidyl ethers of C₂-C₃₀ alkyls;1,2 epoxies of C₃-C₃₀ alkyls; mono and multi glycidyl ethers ofaliphatic alcohols and polyols such as 1,4-butanediol, neopentyl glycol,cyclohexane dimethanol, dibromo neopentyl glycol, trimethylol propane,polytetramethylene oxide, polyethylene oxide, polypropylene oxide,glycerol, and alkoxylated aliphatic alcohols and polyols.

In one embodiment, it is preferred that the aliphatic epoxies compriseone or more cycloaliphatic ring structures. For instance, the aliphaticepoxies may have one or more cyclohexene oxide structures, e.g. twocyclohexene oxide structures. Examples of aliphatic epoxies comprising aring structure include hydrogenated bisphenol A diglycidyl ethers,hydrogenated bisphenol F diglycidyl ethers, hydrogenated bisphenol Sdiglycidyl ethers, bis(4-hydroxycyclohexyl)methane diglycidyl ether,2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether,3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate,3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate,di(3,4-epoxycyclohexylmethyl)hexanedioate,di(3,4-epoxy-6-methylcyclohexylmethyl)hexanedioate,ethylenebis(3,4-epoxycyclohexanecarboxylate),ethanedioldi(3,4-epoxycyclohexylmethyl)ether, and2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-1,3-dioxane.

Examples of aliphatic epoxies are also listed in U.S. Pat. No.6,410,127, which is hereby incorporated in its entirety by reference.

In one embodiment, the present compositions comprise, relative to thetotal weight of the composition, at least 5 wt % of one or morealiphatic epoxies, for instance at least 8 wt %, at least 10 wt %, or atleast 12 wt %. Generally, the present compositions will comprise,relative to the total weight of the composition, less than 50 wt % ofaliphatic epoxies, for instance less than 40 wt %, less than 30 wt %,less than 25 wt %, or less than 20 wt %.

(A2) Oxetane-Functional Components

The present compositions may comprise one or more oxetane-functionalcomponents (“oxetanes”). Oxetanes are components comprising one or moreoxetane groups, i.e. one or more four-member ring structures accordingto formula (5):

Examples of oxetanes include components represented by the followingformula (6):

wherein

-   -   Q₁ represents a hydrogen atom, an alkyl group having 1 to 6        carbon atoms (such as a methyl, ethyl, propyl, or butyl group),        a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group,        an aryl group, a furyl group, or a thienyl group;    -   Q₂ represents an alkylene group having 1 to 6 carbon atoms (such        as a methylene, ethylene, propylene, or butylene group), or an        alkylene group containing an ether linkage, for example, an        oxyalkylene group, such as an oxyethylene, oxypropylene, or        oxybutylene group    -   Z represents an oxygen atom or a sulphur atom; and    -   R₂ represents a hydrogen atom, an alkyl group having 1-6 carbon        atoms (e.g. a methyl group, ethyl group, propyl group, or butyl        group), an alkenyl group having 2-6 carbon atoms (e.g. a        1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group,        2-methyl-2-propenyl group, 1-butenyl group, 2-butenyl group, or        3-butenyl group), an aryl group having 6-18 carbon atoms (e.g. a        phenyl group, naphthyl group, anthranyl group, or phenanthryl        group), a substituted or unsubstituted aralkyl group having 7-18        carbon atoms (e.g. a benzyl group, fluorobenzyl group, methoxy        benzyl group, phenethyl group, styryl group, cynnamyl group,        ethoxybenzyl group), an aryloxyalkyl group (e.g. a phenoxymethyl        group or phenoxyethyl group), an alkylcarbonyl group having 2-6        carbon atoms (e.g. an ethylcarbonyl group, propylcarbonyl group,        or butylcarbonyl group), an alkoxy carbonyl group having 2-6        carbon atoms (e.g. an ethoxycarbonyl group, propoxycarbonyl        group, or butoxycarbonyl group), an N-alkylcarbamoyl group        having 2-6 carbon atoms (e.g. an ethylcarbamoyl group,        propylcarbamoyl group, butylcarbamoyl group, or pentylcarbamoyl        group), or a polyethergroup having 2-1000 carbon atoms.

Preferred oxetanes include those wherein

-   -   Q₁ represents a C₁-C₄ alkyl group (e.g. an ethyl group),    -   Z represents an oxygen atom,    -   Q₂ represents a methylene group, and/or    -   R₂ represents a hydrogen atom, a C₁-C₈ alkyl group, or a        phenylgroup.

Some further examples of oxetanes include the following: Oxetanescontaining one oxetane ring in the molecule include, for instance,3-ethyl-3-hydroxymethyloxetane, 3-(meth)allyloxymethyl-3-ethyloxetane,(3-ethyl-3-oxetanylmethoxy)methylbenzene,(3-ethyl-3-oxetanylmethoxy)benzene,4-fluoro-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,4-methoxy-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,[1-(3-ethyl-3-oxetanylmethoxy)ethyl]phenyl ether,isobutoxymethyl(3-ethyl-3-oxetanylmethyl)ether,isobornyloxyethyl(3-ethyl-3-oxetanylmethyl)ether,isobornyl(3-ethyl-3-oxetanylmethyl)ether,2-ethylhexyl(3-ethyl-3-oxetanyl methyl)ether, ethyldiethyleneglycol(3-ethyl-3-oxetanylmethyl)ether,dicyclopentadiene(3-ethyl-3-oxetanylmethyl)ether,dicyclopentenyloxyethyl(3-ethyl-3-oxetanylmethyl)ether,dicyclopentenyl(3-ethyl-3-oxetanylmethyl)ether,tetrahydrofurfuryl(3-ethyl-3-oxetanylmethyl)ether,tetrabromophenyl(3-ethyl-3-oxetanylmethyl)ether,2-tetrabromophenoxyethyl(3-ethyl-3-oxetanylmethyl)ether,tribromophenyl(3-ethyl-3-oxetanylmethyl)ether,2-tribromophenoxyethyl(3-ethyl-3-oxetanylmethyl)ether,2-hydroxyethyl(3-ethyl-3-oxetanyl methyl)ether,2-hydroxypropyl(3-ethyl-3-oxetanylmethyl)ether,butoxyethyl(3-ethyl-3-oxetanylmethyl)ether,pentachlorophenyl(3-ethyl-3-oxetanylmethyl)ether,pentabromophenyl(3-ethyl-3-oxetanylmethyl)ether,bornyl(3-ethyl-3-oxetanylmethyl)ether, 2-phenyl-3,3-dimethyl-oxetane,and 2-(4-methoxyphenyl)-3,3-dimethyl-oxetane.

Oxetanes containing two or more oxetane rings in the molecule include,for instance, 3,7-bis(3-oxetanyl)-5-oxa-nonane,3,3′-(1,3-(2-methylenyl)propanediylbis(oxymethylene))bis-(3-ethyloxetane),1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene,1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane,1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether, dicyclopentenylbis(3-ethyl-3-oxetanylmethyl)ether, triethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether, tetraethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether,tricyclodecanediyldimethylene(3-ethyl-3-oxetanylmethyl)ether,trimethylolpropane tris(3-ethyl-3-oxetanylmethyl)ether,1,4-bis(3-ethyl-3-oxetanylmethoxy)butane,1,6-bis(3-ethyl-3-oxetanylmethoxy)hexane, pentaerythritoltris(3-ethyl-3-oxetanylmethyl)ether, pentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl)ether, polyethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritolhexakis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritolpentakis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl)ether, caprolactone-modifieddipentaerythritol hexakis(3-ethyl-3-oxetanylmethyl)ether,caprolactone-modified dipentaerythritolpentakis(3-ethyl-3-oxetanylmethyl)ether, ditrimethylolpropanetetrakis(3-ethyl-3-oxetanylmethyl)ether, ethoxylated bisphenol Abis(3-ethyl-3-oxetanylmethyl)ether, propoxylated bisphenol Abis(3-ethyl-3-oxetanylmethyl)ether, ethoxylated hydrogenated bisphenol Abis(3-ethyl-3-oxetanylmethyl)ether, propoxylated hydrogenated bisphenolA bis(3-ethyl-3-oxetanylmethyl)ether, ethoxylated bisphenol F(3-ethyl-3-oxetanylmethyl)ether.

In one embodiment, the present compositions comprise, relative to thetotal weight of the composition, at least 5 wt % of one or moreoxetanes, e.g. at least 8 wt %, at least 10 wt %, at least 12 wt %, orat least 14 wt %. Generally, the present compositions comprise less than50 wt % of oxetanes, e.g. less than 40 wt %, less than 35 wt %, lessthan 30 wt %, or less than 25 wt %.

(B) Free Radical Polymerizable Components

In addition to one or more cationically curable components, the presentinvention may comprise one or more free radical curable components, e.g.one or more free radical polymerizable components having one or moreethylenically unsaturated groups, such as (meth)acrylate (i.e. acrylateand/or methacrylate) functional components.

Examples of monofunctional ethylenically unsaturated components includeacrylamide, N,N-dimethylacrylamide, (meth)acryloylmorpholine,7-amino-3,7-dimethyloctyl(meth)acrylate,isobutoxymethyl(meth)acrylamide, isobornyloxyethyl(meth)acrylate,isobornyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, ethyldiethyleneglycol(meth)acrylate, t-octyl(meth)acrylamide,diacetone(meth)acrylamide, dimethylaminoethyl(meth)acrylate,diethylaminoethyl(meth)acrylate, lauryl(meth)acrylate,dicyclopentadiene(meth)acrylate, dicyclopentenyloxyethyl(meth)acrylate,dicyclopentenyl(meth)acrylate,N,N-dimethyl(meth)acrylamidetetrachlorophenyl(meth)acrylate,2-tetrachlorophenoxyethyl(meth)acrylate,tetrahydrofurfuryl(meth)acrylate, tetrabromophenyl(meth)acrylate,2-tetrabromophenoxyethyl(meth)acrylate,2-trichlorophenoxyethyl(meth)acrylate, tribromophenyl(meth)acrylate,2-tribromophenoxyethyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate,2-hydroxypropyl(meth)acrylate, vinylcaprolactam, N-vinylpyrrolidone,phenoxyethyl(meth)acrylate, butoxyethyl(meth)acrylate,pentachlorophenyl(meth)acrylate, pentabromophenyl(meth)acrylate,polyethylene glycol mono(meth)acrylate, polypropylene glycolmono(meth)acrylate, bornyl(meth)acrylate, and, methyltriethylenediglycol(meth)acrylate.

Examples of the polyfunctional ethylenically unsaturated componentsinclude ethylene glycol di(meth)acrylate, dicyclopentenyldi(meth)acrylate, triethylene glycol diacrylate, tetraethylene glycoldi(meth)acrylate, tricyclodecanediyldimethylene di(meth)acrylate,trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropanetri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate,tripropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate,both-terminal (meth)acrylic acid adduct of bisphenol A diglycidyl ether,1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,polyethylene glycol di(meth)acrylate, (meth)acrylate-functionalpentaerythritol derivatives (e.g. pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, dipentaerythritolhexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, ordipentaerythritol tetra(meth)acrylate), ditrimethylolpropanetetra(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate,propoxylated bisphenol A di(meth)acrylate, ethoxylated hydrogenatedbisphenol A di(meth)acrylate, propoxylated-modified hydrogenatedbisphenol A di(meth)acrylate, and ethoxylated bisphenol Fdi(meth)acrylate.

In one embodiment, the present compositions comprise one or morecomponents having at least 3 (meth)acrylate groups, for instance 3-6(meth)acrylate groups or 5-6 (meth)acrylate groups.

If present, the compositions may comprise, relative to the total weightof the composition, at least 3 wt % of one or more free radicalpolymerizable components, for instance at least 5 wt % or at least 9 wt%. Generally, the compositions comprise, relative to the total weight ofthe composition, less than 50 wt % of free radical polymerizablecomponents, for instance less than 35 wt %, less than 25 wt %, less than20 wt %, or less than 15 wt %.

(C) Hydroxy-Functional Components

Preliminarily, hydroxy-functional components in this section (C) areunderstood to be absent curable groups (such as, e.g., acrylate-,epoxy-, or oxetane groups) and to be not selected from the groupconsisting of photoinitiators.

The present compositions may comprise one or more hydroxy-functionalcomponents. Hydroxy-functional components may be helpful in furthertailoring mechanical properties of the present compositions upon cure.Hydroxy-functional components include monols (hydroxy-functionalcomponents comprising one hydroxy group) and polyols (hydroxy-functionalcomponents comprising more than one hydroxy group).

Representative examples of hydroxy-functional components includealkanols, monoalkyl ethers of polyoxyalkyleneglycols, monoalkyl ethersof alkyleneglycols, alkylene and arylalkylene glycols, such as1,2,4-butanetriol, 1,2,6-hexanetriol, 1,2,3-heptanetriol,2,6-dimethyl-1,2,6-hexanetriol,(2R,3R)-(−)-2-benzyloxy-1,3,4-butanetriol, 1,2,3-hexanetriol,1,2,3-butanetriol, 3-methyl-1,3,5-pentanetriol, 1,2,3-cyclohexanetriol,1,3,5-cyclohexanetriol, 3,7,11,15-tetramethyl-1,2,3-hexadecanetriol,2-hydroxymethyltetrahydropyran-3,4,5-triol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,3-cyclopentanediol,trans-1,2-cyclooctanediol, 1,16-hexadecanediol,3,6-dithia-1,8-octanediol, 2-butyne-1,4-diol, 1,3-propanediol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol,1,8-octanediol, 1,9-nonanediol, 1-phenyl-1,2-ethanediol,1,2-cyclohexanediol, 1,5-decalindiol, 2,5-dimethyl-3-hexyne-2,5-diol,2,7-dimethyl-3,5-octadiyne-2-7-diol, 2,3-butanediol,1,4-cyclohexanedimethanol, polyoxyethylene and polyoxypropylene glycolsand triols of molecular weights from about 200 to about 10,000,polytetramethylene glycols of varying molecular weight,poly(oxyethylene-oxybutylene) random or block copolymers, copolymerscontaining pendant hydroxy groups formed by hydrolysis or partialhydrolysis of vinyl acetate copolymers, polyvinylacetal resinscontaining pendant hydroxyl groups; hydroxy-functional (e.g.hydroxy-terminated) polyesters and hydroxy-functional (e.g.hydroxy-terminated) polylactones, aliphatic polycarbonate polyols (e.g.an aliphatic polycarbonate diol), hydroxy-functional (e.g.hydroxy-terminated) polyethers (e.g. polytetrahydrofuran polyols havinga number average molecular weight in the range of 150-4000 g/mol,150-1500 g/mol, or 150-750 g/mol), and combinations thereof.

In one embodiment, the compositions are absent substantial amounts ofhydroxy-functional components. The absence of substantial amounts ofhydroxy-functional components may decrease the hygroscopicity of thecompositions and/or articles obtained therewith. For instance, thecompositions may comprise, relative to the total weight of thecomposition, less than 15 wt %, less than 10 wt %, less than 6 wt %,less than 4 wt %, less than 2 wt %, or about 0 wt % ofhydroxy-functional components.

(D) Cationic Photoinitiators

The present compositions preferably comprise one or more cationicphotoinitiators, i.e. photoinitiators that, upon exposure to actinicradiation, form cations that can initiate the reactions of cationicallypolymerizable components, such as epoxies or oxetanes.

Examples of cationic photoinitiators include, for instance, onium saltswith anions of weak nucleophilicity. Examples include halonium salts,iodosyl salts or sulfonium salts, such as are described in publishedEuropean patent application EP 153904 and WO 98/28663, sulfoxoniumsalts, such as described, for example, in published European patentapplications EP 35969, 44274, 54509, and 164314, or diazonium salts,such as described, for example, in U.S. Pat, Nos. 3,708,296 and5,002,856. All eight of these disclosures are hereby incorporated intheir entirety by reference. Other examples of cationic photoinitiatorsinclude metallocene salts, such as described, for instance, in publishedEuropean applications EP 94914 and 94915, which applications are bothhereby incorporated in their entirety by reference.

In one embodiment, the present compositions comprise one or morephotoinitiators represented by the following formula (7) or (8):

wherein

-   -   Q₃ represents a hydrogen atom, an alkyl group having 1 to 18        carbon atoms, or an alkoxyl group having 1 to 18 carbon atoms;    -   M represents a metal atom, e.g. antimony;    -   Z represents a halogen atom, e.g. fluorine; and    -   t is the valent number of the metal, e.g. 5 in the case of        antimony.

In one embodiment, the present compositions comprise, relative to thetotal weight of the composition, 0.1-15 wt % of one or more cationicphotoinitiators, for instance 1-10 wt %.

(E) Free Radical Photoinitiators

The compositions may employ one or more free radical photoinitiators.Examples of free radical photoinitiators include benzophenones (e.g.benzophenone, alkyl-substituted benzophenone, or alkoxy-subsitutedbenzophenone); benzoins, e.g. benzoin, benzoin ethers, such as benzoinmethyl ether, benzoin ethyl ether, and benzoin isopropyl ether, benzoinphenyl ether, and benzoin acetate; acetophenones, such as acetophenone,2,2-dimethoxyacetophenone, 4-(phenylthio)acetophenone, and1,1-dichloroacetophenone; benzil, benzil ketals, such as benzil dimethylketal, and benzil diethyl ketal; anthraquinones, such as2-methylanthraquinone, 2-ethylanthraquinone, 2-tertbutylanthraquinone,1-chloroanthraquinone, and 2-amylanthraquinone; triphenylphosphine;benzoylphosphine oxides, such as, for example,2,4,6-trimethylbenzoyldiphenylphosphine oxide; thioxanthones andxanthones, acridine derivatives, phenazene derivatives, quinoxalinederivatives or I-phenyl-1,2-propanedione-2-O-benzoyloxime, I-aminophenylketones or I-hydroxyphenyl ketones, such as I-hydroxycyclohexyl phenylketone, phenyl (1-hydroxyisopropyl)ketone and4-isopropylphenyl(1-hydroxyisopropyl)ketone, or triazine compounds, forexample, 4′″ -methyl thiophenyl-1-di(trichloromethyl)-3,5-S-triazine,S-triazine-2-(stilbene)-4,6-bistrichloromethyl, and paramethoxy styryltriazine.

Further suitable free radical photoinitiators include the ionicdye-counter ion compounds, which are capable of absorbing actinic raysand producing free radicals, which can initiate the polymerization ofthe acrylates. See, for example, published European Patent Application223587, and U.S. Pat. Nos. 4,751,102, 4,772,530 and 4,772,541, all fourof which are hereby incorporated in their entirety by reference.

In one embodiment, the present compositions comprise, relative to thetotal weight of the composition, 0.1-15 wt % of one or more free radicalphotoinitiators, for instance 1-10 wt %.

(F) Additives

Additives may also be present in the composition of the invention.Stabilizers are sometimes added to the compositions in order to preventa viscosity build-up, for instance a viscosity build-up during usage ina solid imaging process. Preferred stabilizers include those describedin U.S. Pat. No. 5,665,792, the entire disclosure of which is herebyincorporated by reference. Such stabilizers are usually hydrocarboncarboxylic acid salts of group IA and IIA metals. Most preferredexamples of these salts are sodium bicarbonate, potassium bicarbonate,and rubidium carbonate. Alternative stabilizers arepolyvinylpyrrolidones and polyacrylonitriles. Other possible additivesare dyes, including dyes that change color upon cure. Examples ofcolor-changing dyes include COPIKEM 20(3,3-bis(1-butyl-2-methyl-H-indol-3-yl)-1-(3H)-isobenzofuranone),COPIKEM 5(2′-di(phenylmethy)amino-6′-(diethylamino)spiro(isobenzofuran-1(3H),9′-(9H)xanthen)-3-one),COPIKEM 14 ( a substituted phthalide), COPIKEM 7(3-{(4-dimethylamino)-phenyl}-3-(1-butyl-2-methylindol-3-yl)-6-dimethyamino)-1(3H)-isobenzofuranone),and COPIKEM 37(2-(2-octoxyphenyl)-4-(4-dimethylaminophenyl)-6-(phenyl)pyridine). Ifpresent, the amount of color-changing dyes in the compositions is,relative to the total weight of the composition, preferably at least0.0001 wt %, for instance at least 0.0005 wt %. In one embodiment, theamount of dye is, relative to the total weight of the composition, lessthan 1 wt %, e.g. less than 0.1 wt %. Even further examples of additivesinclude antioxidants, wetting agents, antifoaming agents, thickeningagents, photosensitizers (e.g. n-ethyl carbazole, benzoperylene,1,8-diphenyl-1,3,5,7-octatetraene, or 1,6-diphenyl-1,3,5-hexatriene),and metallic-, organic-, inorganic-, or organic-inorganic hybrid fillers(e.g. silica particles, glass beads, or talc). The size of the fillersmay vary and can be, for instance, in the nanometer range or in themicrometer range. In one embodiment, the present compositions comprise,relative to the total weight of the composition, less than 20 wt % offillers, e.g. less than 10 wt %, less than 5 wt %, or about 0 wt %. Inanother embodiment, the present compositions comprise, relative to thetotal weight of the composition, up to 90 wt % of filler, e.g. 20-90 wt%, 40-90 wt %, or 60-90 wt %.

Physical Parameters

The present compositions, after full cure, preferably have a heatdeflection temperature (“HDT”) under a pressure of 1.82 MPa (264 psi) ofat least 105° C., for instance at least 110° C., at least 115° C., atleast 120° C., or at least 125° C. The HDT (1.82 MPa) is generally below300° C.

The present compositions, after full cure, preferably have an elongationat break of at least 1.5%, for instance at least 2.0%, at least 2.5%, atleast 3%, or at least 3.5%. The elongation at break is generally below50%.

The present compositions preferably have an E10 cure speed of less than85 mJ/cm², for instance less than 80 mJ/cm², less than 70 mJ/cm², lessthan 60 mJ/cm², less than 55 mJ/cm², less than 50 mJ/cm², or less than45 mJ/cm².

The physical condition of the present compositions may vary and can be,for instance, a liquid, a gel, a paste, or a solid. If the compositionis a liquid, it preferably has a viscosity, at 30° C., of less than 1000mPas, for instance less than 750 mPas, less than 650 mPas, less than 550mPas, less than 450 mPas, or less than 350 mPas.

The present compositions, after full cure, preferably have a tensilestrength of at least 35 MPa, for instance at least 40 MPa, at least 50MPa, at least 60 MPa, or at least 70 MPa.

The present compositions, after full cure, preferably have a Young'smodulus of at least 1500 MPa, for instance at least 2000 MPa, at least2500 MPa, at least 2750 MPa, or at least 3000 MPa.

The present compositions, after full cure, preferably have a glasstransition temperature (Tg) of at least 105° C., for instance at least110° C., at least 120° C., at least 130° C., at least 140° C., or atleast 150° C. The Tg is generally below 300° C.

Applications

The present compositions may be used, for instance, as coatingcompositions or as compositions for preparing a three dimensional objectby rapid prototyping. The compositions may be cured by heat or anysuitable form of radiation, e.g. electron beam radiation or actinicradiation, or mixtures thereof. For instance, the composition may firstbe cured to a certain extent by radiation and subsequently be post-curedby heat.

Rapid prototyping, sometimes also referred to as “solid imaging” or“stereolithography”, concerns the imagewise curing of successive thinlayers of a curable composition to form a three-dimensional object. See,e.g., U.S. Pat. Nos. 4,987,044; 5,014,207; 5,474,719; 5,476,748; and5,707,780; which are all five hereby incorporated in their entirety byreference. A rapid prototyping process may for instance be described as:

-   -   (1) coating a layer of a composition onto a surface;    -   (2) exposing said layer imagewise to actinic radiation to form        an imaged cross-section;    -   (3) coating a further layer of the composition onto said imaged        cross-section;    -   (4) exposing said further layer imagewise to actinic radiation        to form an additional imaged cross-section;    -   (5) repeating steps (3) and (4) a sufficient number of times in        order to build up a three-dimensional article;    -   (6) optionally, post-curing the three-dimensional article.

The following examples are given as particular embodiments of theinvention and to demonstrate the practice and advantages thereof. It isto be understood that the examples are given by way of illustration andare not intended to limit the specification or the claims that follow inany manner.

EXAMPLES

TABLE 1 Glossary Commercial Name (Supplier) Description EPON 825(Resolution Performance bisphenol A diglycidyl Products) ether (aromaticepoxy) EPICLON N-740 (Dainippon Ink & phenol epoxy novolac Chemical)(aromatic epoxy) HELOXY 64 (Resolution Performance nonylphenyl glycidylProducts) ether (aromatic epoxy) UVACURE 1500 (UCB Radcure) 3,4-epoxycyclohexyl methyl-3,4-epoxy cyclohexyl carboxylate (aliphatic epoxy) UVR6000 (Dow Chemical) 3-ethyl-3-hydroxymethyl- oxetane (oxetane) SR-399(Sartomer) monohydroxy dipentaerythritol pentaacrylate IRGACURE 184(Ciba Geigy) 1-hydroxycyclohexyl phenyl ketone DAROCURE 1173 (CibaGeigy) 2-hydroxy-2-methyl-1-phenyl- 1-propanone CPI-6976 (Aceto) mixtureof triarysulfonium hexafluoroantimonate salts SILWET L-7600 (OSISpecialities) surfactant BYK-A-501 (BYK-Chemie) defoamer PVP (Aldrich)stabilizer (polyvinylpyrolidone, Mw ca. 10,000)

Compositions were prepared by mixing the components listed in Table 2(Examples 1-8) and Table 3 (Comparative Examples A-B), with amounts ofthe components being listed in parts by weight. The thus preparedcompositions were subsequently analyzed in accordance with the TestMethods described below. The test results are also listed in Tables 2and 3. TABLE 2 Examples 1-8 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7Ex. 8 Ingredients EPON 825 42 39 50 42.1 40.5 34.0 42.4 38.4 EPICLONN-740 8 16 13 12.5 13.4 12.3 17.5 HELOXY 64 3.8 UVACURE 1500 12.5 12.512.5 12.5 12.0 20.2 12.5 13 UVR 6000 20 15 20 15.5 15.5 15.5 16 16.6SR399 12 12 12 11 10.6 11.0 11 9.2 CPI 6976 4 4 4 2.8 2.7 4 4 4 IRGACURE184 1.5 1.5 1.5 2.8 2.7 1.6 1.6 DAROCURE 1173 1.6 SILWET L-7600 0.2 0.20.2 0.2 0.2 0.2 0.2 0.2 BYK A501 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02PVP 0.005 0.005 0.005 0.005 0.005 0.005 0.005 Test results E_(c)[mJ/cm²] 10.3 8.4 6.8 8.7 9.9 5.2 9.6 7.8 D_(p) [μm] 130 117 137 140 152112 130 122 E10 [mJ/cm²] 73.4 73.6 44.3 53.5 51.8 49.9 68.9 61.8 T_(g)[° C.] 129.8 151 118 132 127 135 131 127 HDT (1.82 MPa) [° C.] 110.7129.3 109 125.5 119.6 Young's modulus [MPa] 3013 3131 3000 2951 30483083 3138 3000 Elongation at break [%] 3.7 2.6 3.5 3.3 3.7 2.3 2.0 1.7Tensile Strength [MPa] 71.4 60.8 71.4 68.7 75.2 55.7 49.7 46.0Viscosity, 30° C. [mPas] 334 675 275 575 520 420 490

TABLE 3 Comparative Examples A and B Comp. Ex. A Comp. Ex. B IngredientsEPON 825 49.6 52.8 EPICLON N-740 16 16 UVR 6000 16 16.6 SR399 12 10.5CPI 6976 3.6 4 IRGACURE 184 2.6 1.8 DAROCURE 1173 0.2 0.2 SILWET L-76000.02 0.02 BYK A501 0.005 0.005 Test results Ec [mJ/cm²] 14.4 20.8 Dp[μm] 140 140 E10 [mJ/cm²] 88.2 126.9 T_(g) [° C.] 123 91 Young's modulus[MPa] 2979 3028 Elongation at break [%] 2.5 3.5 Tensile Strength after[MPa] 59.6 71.6 Viscosity, 30° C. [mPas] 850Test Methods(a) Tensile Strength, Young's Modulus, and Elongation at Break

Tensile data was obtained by testing tensile bars (“dogbones”) made byfirst consecutively imaging 150 μm thick layers of the composition to betested in a rapid prototyping machine. Each cross-sectional layer of thetensile bar was given exposure sufficient to polymerize the compositionat a 250 μm depth, providing approximately 100 μm of overcure orengagement cure to assure adhesion to the previously coated and exposedlayer. The layers were exposed with a laser emitting in the ultraviolet(UV) region at 354.7 nm. The resulting tensile bars/dogbones wereapproximately 150 mm long and had a cross-section in the narrowedportion of approximately 1 cm×1 cm. After preparation of the tensile barin the rapid prototyping machine, the tensile bar was removed from themachine, washed with tri(propyleneglycol)methyl ether (“TPM”) andisopropanol, and placed in a post-curing apparatus (“PCA” sold by 3-DSystems, 10 bulb unit using Phillips TLK/05 40 W bulbs). In the PCA, thetensile bar was post-cured first by subjecting it to 60 minutes of UVradiation at room temperature. After these 60 minutes, the UV radiationwas stopped and the tensile bar was subjected to 160° C. for two hours.The procedure of rapid prototyping a composition and post-curing acomposition in the manner just described is understood herein to resultin fully cured samples. The tensile tests to determine tensile strength,Young's modulus, and elongation at break were run one day afterpreparation of the tensile bar and in accordance with ASTM D638, whichis hereby incorporated in its entirety by reference, except that noprovision was made for controlling the room temperature and humidity andthe bars were not equilibrated for 2 days. The reported data is theaverage of three measurements.

(b) Viscosity

The composition was added to a 250-mL screw cap bottle and heated to 30°C. by placing it in a 30° C. bath for at least one hour. The viscosityof the composition was then determined with a Brookfield DV-II+Viscometer employing a #3 spindle.

(c) Glass Transition Temperature (T_(g))

A fully cured specimen was prepared in the same manner as describedabove for the preparation of a tensile bar. Part of the specimen wasplaced in a TA Instruments TMA 2940 at room temperature. The specimenwas then heated with a ramp of 3° C./min from room temperature to 250°C. under a nitrogen purge of 60 mL/min. A graph of dimension change overtemperature was generated and analyzed by using TA Instrument UniversalAnalysis V2.6D software, which calculated the glass transitiontemperature from a sudden change in the slope of the thermal expansioncurve.

(d) Heat Deflection Temperature (HDT)

Fully cured specimens for determining the HDT were prepared in the samemanner as the above tensile bars, except that the dimensions of thespecimens for the HDT measurements were 5 inch (12.7 cm) in length and0.5×0.5 inch (12.7 mm×12.7 mm) in cross-section. The HDT (under apressure of 1.82 MPa) of the specimens was then determined according toASTM D648-00a Method B, which is hereby incorporated in its entirety byreference, employing an ATLAS HDV2 Automated instrument.

(e) E10, D_(p), and E_(c)

The photoproperties E_(c)(mJ/cm²), D_(p) (μm), and E10 (mJ/cm²)represent the photoresponse (in this case thickness of layer formed) ofa particular formulation to exposure by a single wavelength or range ofwavelengths. In the instant Examples and Comparative Examples, at least20 grams of composition was poured into a 100 mm diameter petri-dish andallowed to equilibrate to approximately 30° C. and 30% RH. The sampleswere then scanned in a line-by-line fashion using a focused laser beamof approximately 100-140 mW. The laser, a frequency tripled YAG laser,had an output wavelength of 354.7 nm and was pulsed at 80 KHz. Theexposures were made in a square pattern approximately 20 mm by 20 mm.Six individual exposures were made at near constant laser power but atvarious scan speeds. The parallel scan lines making up each exposurewere drawn approximately 50 μm apart. Based upon knowledge of thediameter of the focused beam at the liquid surface, the scan speed, thelaser power, and the scan spacing, the summation of exposure mJ/cm² wascalculated. Each square was allowed to float on the surface of thepetri-dish for approximately 15 minutes. Then the squares were blottedand a thickness measurement was taken using Mitutoyo NTO25-8′C springloaded Absolute Digimatic calipers. When the natural log of theexposures is plotted against the measured thickness a least squares fitline can be drawn. The D_(p) (μm) is the slope of the least squares fitline. The E_(c) (mJ/cm²) is the X-axis crossing point (Y=0) of the line.And the E10 is the energy necessary to produce a layer approximately 10mils (254 μm) thick. In general, the lower the E10 number, the fasterthe photospeed of the composition.

Having described specific embodiments of the present invention, it willbe understood that many modifications thereof will readily be apparentto those skilled in the art, and it is intended therefore that thisinvention is limited only by the spirit and scope of the followingclaims.

1. A curable rapid prototyping composition comprising: (i) one or morearomatic epoxies; and (ii) one or more aliphatic epoxies; wherein saidcomposition, after full cure, has a heat deflection temperature (1.82MPa) of at least 105° C. and an elongation at break of at least 1.5%. 2.The composition of claim 1, wherein said composition comprises two ormore aromatic epoxies.
 3. The composition according to claim 1, whereinsaid composition comprises at least 25 wt %, relative to the totalweight of the composition, of said one or more aromatic epoxies.
 4. Thecomposition according to claim 1, wherein said composition comprises atleast 50 wt %, relative to the total weight of the composition, of saidone or more aromatic epoxies.
 5. The composition according to claim 1,wherein said composition further comprises one or more oxetanes.
 6. Thecomposition according to claim 5, wherein said composition comprises5-40 wt %, relative to the total weight of the composition, of said oneor more oxetanes.
 7. The composition according to claim 1, wherein saidone or more aliphatic epoxies consist essentially of epoxies comprisinga cycloaliphatic ring structure.
 8. The composition according to claim1, wherein said one or more aliphatic epoxies include an epoxycomprising two cyclohexene oxide structures.
 9. The compositionaccording to claim 1, wherein said composition comprises 5-30 wt % ofsaid one or more aliphatic epoxies.
 10. The composition according toclaim 1, wherein said composition comprises an epoxy having no more thanone epoxy group.
 11. The composition according to claim 1, wherein saidcomposition further comprises one or more free radical polymerizablecomponents.
 12. The composition of claim 11, wherein said one or morefree radical polymerizable components include a component having 5 or 6(meth)acrylate groups.
 13. The composition according to claim 11,wherein said composition comprises 5-25 wt %, relative to the totalweight of the composition, of said one or more free radicalpolymerizable component.
 14. The composition according to claim 1,wherein said one or more aromatic epoxies include a phenol epoxy novolacand/or a cresol epoxy novolac.
 15. The composition according to claim 1,wherein said one or more aromatic epoxies includes a bisphenoldiglycidyl ether.
 16. The composition according to claim 1, wherein saidcomposition comprises a (meth)acrylate functional pentaerythritolderivative.
 17. The composition according to claim 1, wherein saidcomposition further comprises a cationic photoinitiator and a freeradical photoinitiator.
 18. The composition according to claim 1,wherein said composition comprises about 0-4 wt % of hydroxy-functionalcomponents that are absent a curable group and are not selected from thegroup consisting of photoinitiators.
 19. The composition according toclaim 1, wherein said heat deflection temperature is at least 115° C.20. The composition according to claim 1, wherein said heat deflectiontemperature is at least 125° C.
 21. The composition according to claim1, wherein said elongation to break is at least 2%.
 22. The compositionaccording to claim 1, wherein said elongation to break is at least 3%.23. The composition according to claim 1, wherein said composition hasan E10 cure speed of less than 80 mJ/cm2.
 24. The composition accordingto claim 1, wherein said composition has a viscosity of less than 750mPas at 30° C.
 25. The composition according to claim 1, wherein saidcomposition, after full cure, has a tensile strength of at least 35 MPa.26. The composition according to claim 1, wherein said composition,after full cure, has a modulus of at least 2000 MPa.
 27. The compositionaccording to claim 1, wherein said composition comprises acolor-changing dye.
 28. A curable composition having an E10 cure speedof less than 80 mJ/cm² and, after cure by radiation and heat, a heatdeflection temperature (1.82 MPa) of at least 125° C. and an elongationat break of at least 2.5%.
 29. The composition according to claim 1,wherein said composition comprises, relative to the total weight of thecomposition, about 0 wt % filler.
 30. A rapid prototyping processcomprising: (1) coating a layer of a composition according to claim 1onto a surface; (2) exposing said layer imagewise to actinic radiationto form an imaged cross-section; (3) coating a layer of said compositionaccording to claim 1 onto the previously exposed imaged cross-section;(4) exposing said layer from step (3) imagewise to actinic radiation toform an additional imaged cross-section; (5) repeating steps (3) and (4)a sufficient number of times to form a three-dimensional article.
 31. Anarticle obtainable by the process of claim
 30. 32. Use of a curablerapid prototyping composition comprising one or more aromatic epoxies,one or more aliphatic epoxies for making a three dimensional article,whereby the article has a heat deflection temperature (at 1.82 MPa) ofat least 105° C. and an elongation at break of at least 1.5%.
 33. Useaccording to claim 32, whereby has a heat deflection temperature (1.82MPa) of at least 125° C.
 34. Use according to claims 32, wherein thearticle has an elongation at break of at least 2.5%.